Positive response is a 'Yes' to any of the following questions:

1. Has your child been admitted to a hospital?
2. Has your child experienced an illness that made you fear for his/her life (life-threatening episode) that required attendance to the Emergency Room or a Physician's office?
3. Has your child developed a medical condition that required 3 or more office or emergency room visits for that condition?
4. Has your child been diagnosed by a physician as having:

Low blood count or low platelet count? Swelling or redness of the joints? Asthma? Diabetes? Autism?

SAE: any untoward medical occurrence with the following outcomes:

• death,
• a life-threatening adverse drug experience (as confirmed by the investigators),
• inpatient hospitalization or prolongation of existing hospitalization,
• a persistent or significant disability/incapacity, or
• a congenital anomaly/birth defect. Medical conditions that required 3 or more office or emergency room visits, and diagnosis by a physician of low blood cell count or low platelet count, swelling or redness of the joints, asthma, diabetes, or autism were also solicited. (MedDRA Version 6.0)

Received 4th dose of the Pentacel® series before 2nd birthday

Positive response is a 'Yes' to any of the following questions:

1. Has your child been admitted to a hospital?
2. Has your child experienced an illness that made you fear for his/her life (life-threatening episode) that required attendance to the Emergency Room or a Physician's office?
3. Has your child developed a medical condition that required 3 or more office or emergency room visits for that condition?
4. Has your child been diagnosed by a physician as having:

Low blood count or low platelet count? Swelling or redness of the joints? Asthma? Diabetes? Autism?

Participants who completed the whole survey. Those who had confirmed data, or had data that did not require confirmation, or had unconfirmed data.

Received 4th dose of the Pentacel® series before 2nd birthday